public class EscapeUnescape {
 public static String escape(String src) {
  int i;
  char j;
  StringBuffer tmp = new StringBuffer();
  tmp.ensureCapacity(src.length() * 6);
  for (i = 0; i < src.length(); i++) {
   j = src.charAt(i);
   if (Character.isDigit(j) || Character.isLowerCase(j)
     || Character.isUpperCase(j))
    tmp.append(j);
   else if (j < 256) {
    tmp.append("%");
    if (j < 16)
     tmp.append("0");
    tmp.append(Integer.toString(j, 16));
   } else {
    tmp.append("%u");
    tmp.append(Integer.toString(j, 16));
   }
  }
  return tmp.toString();
 }
 public static String unescape(String src) {
  StringBuffer tmp = new StringBuffer();
  tmp.ensureCapacity(src.length());
  int lastPos = 0, pos = 0;
  char ch;
  while (lastPos < src.length()) {
   pos = src.indexOf("%", lastPos);
   if (pos == lastPos) {
    if (src.charAt(pos + 1) == 'u') {
     ch = (char) Integer.parseInt(src
       .substring(pos + 2, pos + 6), 16);
     tmp.append(ch);
     lastPos = pos + 6;
    } else {
     ch = (char) Integer.parseInt(src
       .substring(pos + 1, pos + 3), 16);
     tmp.append(ch);
     lastPos = pos + 3;
    }
   } else {
    if (pos == -1) {
     tmp.append(src.substring(lastPos));
     lastPos = src.length();
    } else {
     tmp.append(src.substring(lastPos, pos));
     lastPos = pos;
    }
   }
  }
  return tmp.toString();
 }
 /** 
  * @disc 对字符串重新编码 
  * @param src 
  * @return  
  */
 public static String isoToGB(String src) {
  String strRet = null;
  try {
   strRet = new String(src.getBytes("ISO_8859_1"), "GB2312");
  } catch (Exception e) {

  }
  return strRet;
 }

 /** 
  * @disc 对字符串重新编码 
  * @param src 
  * @return  
  */
 public static String isoToUTF(String src) {
  String strRet = null;
  try {
   strRet = new String(src.getBytes("ISO_8859_1"), "UTF-8");
  } catch (Exception e) {

  }
  return strRet;
 }
 public static void main(String[] args) {
  String tmp = "中文";
  System.out.println("testing escape : " + tmp);
  tmp = escape(tmp);
  System.out.println(tmp);
  System.out.println("testing unescape :" + tmp);
  System.out.println(unescape("%u6211%u4eec"));
  System.out.println(isoToUTF(tmp));
 }
}

testing escape : 中文
%u4e2d%u6587
testing unescape :%u4e2d%u6587
我们
%u4e2d%u6587